Although earlier research has shown that individual differences on the spectrum of attention deficit hyperactivity disorder (ADHD) are highly heritable, emerging evidence suggests that symptoms are associated with complex interactions between genes and environmental influences. This study investigated whether a genetic predisposition [Note that the term ‘genetic predisposition’ was used in this manuscript to refer to an estimate based on twin modeling (an individual’s score on the latent trait that resembles additive genetic influences) in the particular population being examined.] for the symptom dimensions hyperactivity and inattention determines the extent to which unique-environmental influences explain variability in these symptoms. To this purpose, we analysed a sample drawn from the Twins Early Development Study (TEDS) that consisted of item-level scores of 2168 16-year-old twin pairs who completed both the Strengths and Difficulties Questionnaire (SDQ; Goodman, in J Child Psychol Psychiatry 38:581–586, 1997) and the Strength and Weaknesses of ADHD Symptoms and Normal Behavior (SWAN; Swanson, in Paper presented at the meeting of the American Psychological Association, Los Angeles, 1981) questionnaire. To maximize the psychometric information to measure ADHD symptoms, psychometric analyses were performed to investigate whether the items from the two questionnaires could be combined to form two longer subscales. In the estimation of genotype-environment interaction, we corrected for error variance heterogeneity in the measurement of ADHD symptoms through the application of item response theory (IRT) measurement models. A positive interaction was found for both hyperactivity (e.g., \({\beta }_{1}\) = 2.20 with 95% highest posterior density interval equal to [1.79;2.65] and effect size equal to 3.00) and inattention (e.g., \({\beta }_{1}\) = 2.16 with 95% highest posterior density interval equal to [1.56;2.79] and effect size equal to 3.07). These results indicate that unique-environmental influences were more important in creating individual differences in both hyperactivity and inattention for twins with a genetic predisposition for these symptoms than for twins without such a predisposition.

尽管早期研究表明注意力缺陷多动障碍 (ADHD) 的个体差异具有高度遗传性，但新出现的证据表明，症状与基因和环境影响之间复杂的相互作用有关。这项研究调查了所检查的特定人群中是否存在遗传倾向[请注意，本手稿中使用的术语“遗传倾向”是指基于双胞胎模型的估计（个体对类似于加性遗传影响的潜在特征的评分） .]对于症状维度的多动和注意力不集中决定了独特环境影响在多大程度上解释了这些症状的变异性。为此，我们分析了从双胞胎早期发展研究 (TEDS) 中抽取的样本，该样本由 2168 对 16 岁双胞胎的项目级分数组成，这些双胞胎完成了优势和困难问卷（SDQ；Goodman，在 J Child 中） Psychol Psychiatry 38:581–586, 1997）以及ADHD 症状和正常行为的强度和弱点（SWAN；Swanson，在美国心理学会会议上提出的论文，洛杉矶，1981 年）调查问卷。为了最大限度地利用心理测量信息来测量多动症症状，我们进行了心理测量分析，以调查两份问卷中的项目是否可以组合起来形成两个更长的子量表。在基因型-环境相互作用的估计中，我们通过应用项目反应理论（IRT）测量模型来纠正 ADHD 症状测量中的误差方差异质性。发现多动（例如，\({\beta }_{1}\) = 2.20，95% 最高后验密度区间等于 [1.79;2.65]，效应大小等于 3.00）和注意力不集中（例如， ，\({\beta }_{1}\) = 2.16，95% 最高后验密度区间等于 [1.56;2.79]，效应大小等于 3.07)。这些结果表明，对于具有这些症状遗传倾向的双胞胎来说，独特的环境影响在造成多动症和注意力不集中的个体差异方面比没有这种倾向的双胞胎更重要。